Improve messaging around various encryption key options

Element has landed on calling these "recovery keys" and we should do the
same. Since these have had various names throughout the years and in
previous versions of NeoChat, they are still mentioned.

I also renamed "Secret Backup" to "Key Storage" which is also Element
terminology.

src/app/qml/UnlockSSSSDialog.qml

@@ -13,7 +13,7 @@ FormCard.FormCardPage {
 
     property bool processing: false
 
-    title: i18nc("@title:window", "Manage Secret Backup")
+    title: i18nc("@title:window", "Manage Key Storage")
 
     topPadding: Kirigami.Units.gridUnit
     leftPadding: 0
@@ -32,7 +32,7 @@ FormCard.FormCardPage {
         function onKeyBackupError(): void {
             securityKeyField.clear()
             root.processing = false
-            banner.text = i18nc("@info:status", "The security key or backup passphrase was not correct.")
+            banner.text = i18nc("@info:status", "The recovery key was not correct.")
             banner.visible = true
         }
 
@@ -45,20 +45,20 @@ FormCard.FormCardPage {
     }
 
     FormCard.FormHeader {
-        title: i18nc("@title", "Unlock using Security Key or Backup Passphrase")
+        title: i18nc("@title", "Unlock using Recovery Key")
     }
     FormCard.FormCard {
         FormCard.FormTextDelegate {
-            description: i18nc("@info", "If you have a security key or backup passphrase for this account, enter it below or upload it as a file.")
+            description: i18nc("@info", "If you have a recovery key (also known as a “security key” or “backup passphrase”), enter it below or upload it as a file.")
         }
         FormCard.FormTextFieldDelegate {
             id: securityKeyField
-            label: i18nc("@label:textbox", "Security Key or Backup Passphrase:")
+            label: i18nc("@label:textbox", "Recovery Key:")
             echoMode: TextInput.Password
         }
         FormCard.FormButtonDelegate {
             id: uploadSecurityKeyButton
-            text: i18nc("@action:button", "Upload from File")
+            text: i18nc("@action:button", "Upload From File")
             icon.name: "cloud-upload"
             enabled: !root.processing
             onClicked: {
@@ -83,12 +83,12 @@ FormCard.FormCardPage {
     }
     FormCard.FormCard {
         FormCard.FormTextDelegate {
-            description: i18nc("@info", "If you have previously verified this device, you can try loading the backup key from other devices by clicking the button below.")
+            description: i18nc("@info", "If you have previously verified this device, you request encryption keys from other verified devices.")
         }
         FormCard.FormButtonDelegate {
             id: unlockCrossSigningButton
             icon.name: "emblem-shared-symbolic"
-            text: i18nc("@action:button", "Request from other Devices")
+            text: i18nc("@action:button", "Request From Other Devices")
             enabled: !root.processing
             onClicked: {
                 root.processing = true

src/settings/NeoChatSecurityPage.qml

@@ -89,7 +89,7 @@ FormCard.FormCardPage {
     FormCard.FormCard {
         FormCard.FormButtonDelegate {
             id: secretBackupDelegate
-            text: i18nc("@action:inmenu", "Manage Secret Backup")
+            text: i18nc("@action:inmenu", "Manage Key Storage")
             description: i18nc("@info", "Import or unlock encryption keys from other devices.")
             icon.name: "unlock"
             onClicked: root.QQC2.ApplicationWindow.window.pageStack.pushDialogLayer(Qt.createComponent('org.kde.neochat', 'UnlockSSSSDialog'), {}, {
@@ -103,7 +103,7 @@ FormCard.FormCardPage {
         FormCard.FormButtonDelegate {
             id: importKeysDelegate
             text: i18nc("@action:button", "Import Keys")
-            description: i18nc("@info", "Import encryption keys from a backup.")
+            description: i18nc("@info", "Import encryption keys from a backup file.")
             icon.name: "document-import"
             onClicked: {
                 let dialog = root.QQC2.ApplicationWindow.window.pageStack.pushDialogLayer(Qt.createComponent("org.kde.neochat.settings", "ImportKeysDialog"), {
@@ -126,7 +126,7 @@ FormCard.FormCardPage {
         FormCard.FormButtonDelegate {
             id: exportKeysDelegate
             text: i18nc("@action:button", "Export Keys")
-            description: i18nc("@info", "Export this device's encryption keys.")
+            description: i18nc("@info", "Export this device's encryption keys to a file.")
             icon.name: "document-export"
             onClicked: {
                 root.QQC2.ApplicationWindow.window.pageStack.pushDialogLayer(Qt.createComponent("org.kde.neochat.settings", "ExportKeysDialog"), {